Building standards - Standard 2.15 Automatic Fire Suppression Systems: cost benefit analysis

5. Analysis of Benefits

5.1 Introduction

5.1.1 This section considers the estimates of the value of benefits (avoided costs) from installing fire suppression systems. The benefits to be assessed are the prevention of deaths and injuries in fires and the reduction in property damage. While one study (reviewed in Section 4) included the benefit of reduced greenhouse gas emissions as a result of a sprinkler-controlled fire, the monetised benefit was found to be very small compared with other benefits. For this research, it is not proposed to consider greenhouse gases further.

5.1.2 The assessment of the benefits from sprinkler systems will require data and assumptions on the prevalence of fires, deaths and injuries per property type; the value of a statistical life, injury and fire damage; and the effectiveness of sprinklers in reducing deaths, injuries and damage. These are all considered in this section which concludes with estimates of the annual benefit of fire suppression systems by building category.

5.2 The Prevalence of Fire

5.2.1 As stated in paragraph 2.1.3, the SFRS dataset classifies building fires into residential dwellings, residential 'other' and non-residential. The buildings covered by Standard 2.15 are primarily residential dwelling buildings, although there are some buildings within residential 'other' and non-residential which are relevant to the analysis.

5.2.2 Comparison of the categories of buildings under Standard 2.15 and the overview of fire statistics shows that the categories of buildings do not correspond exactly. Table 5.1 sets out the proposed allocation of fire data categories to the building categories in Standard 2.15.

5.2.3 The published fire data does not provide a detailed breakdown of the retail category. Compared to the residential dwelling categories, retail has relatively few fires, deaths and injuries. Hence, it is proposed to use the statistics for retail in the analysis as a proxy for 'enclosed shopping centres'.

5.2.4 Social housing is a category in Standard 2.15. but it is not a building type. It is a characteristic of the ownership of the building and the occupier. Paragraph 2.2.10 highlighted that deprivation is strongly associated with the rate of dwelling fires. If it is assumed that social housing is more prevalent in areas of deprivation, it could be expected that the prevalence of fires in social housing would be higher than in mainstream housing. Therefore, to enable the analysis of social housing the fire statistics categories of 'flats' and 'houses' form the basis of the calculation, but prevalence of fires, deaths and injuries is doubled to reflect the higher incidence of fires in deprived areas.

Table 5.1: Allocation of Fire Categories to Standard 2.15 Categories

Standard 2.15 Categories: Fire Statistics Categories

Enclosed shopping centre: Retail

Residential care building: Residential home

Sheltered housing complex: Sheltered housing (self-contained); Sheltered housing (not self-contained)

Building containing flat or maisonette: Flats; Tenements

Social housing dwelling: Flats; Houses

Shared multi-occupancy residential building: HMO

5.2.5 Using the Standard 2.15 categories in Table 5.1 above, Table 5.2 shows the average number of building fires by category over the last five years (2016/17 to 2021/22) and the earlier five year period 2012/13 to 2016/17. The data show a clear reduction in the average number of fires in each category. Similar data are shown for the number of deaths and casualties (non-fatal) from these building fires.

5.2.6 The Table shows that there were no deaths in HMOs in either of the two periods and that the average number of deaths per annum in enclosed shopping centres, residential care buildings and sheltered housing complexes is very low compared to the number of deaths in buildings containing flats/maisonettes and social housing dwellings. A similar trend is also shown for casualties from fires with HMOs, enclosed shopping centres and residential care buildings having low numbers of casualties.

Table 5.2: Average Annual Number of Fires, Deaths and Casualties by Building Type, 2012/13 to 2016/17 and 2017/18 to 2021/22

	2012/13 to 2016/17	2017/18/ to 2021/22
Fires
Enclosed shopping centres	236.4	181.6
Residential care building	149.0	123.8
Sheltered housing complex	551.8	433.6
Building containing flat/maisonette	2,967.8	2,521.6
Social housing dwelling	4,989.2	4,454.6
Share multi-occ. residential building	34.6	26.6
Deaths
Enclosed shopping centres	0.2	0.2
Residential care building	0.8	0.2
Sheltered housing complex	1.6	2.6
Building containing flat/maisonette	15.4	12.8
Social housing dwelling	33.0	30.4
Share multi-occ. residential building	0.0	0.0
Casualties
Enclosed shopping centres	6	6
Residential care building	8	5
Sheltered housing complex	70	48
Building containing flat/maisonette	649	519
Social housing dwelling	1,008	826
Share multi-occ. residential building	6	3

5.2.7 The average annual data for 2017/18 to 2021/22 in Table 5.2 has been used to calculate the prevalence of fires, deaths and casualties in each of the building categories. Prevalence is calculated as the number of fires, deaths and casualties per 10,000 properties in each building category and is shown in Table 5.3. The total stock of buildings in each category is also shown in the Table.

5.2.8 When account is taken of the number of buildings of each type in Scotland, the prevalence of fires is relatively high in residential care buildings and to a lesser extent sheltered housing. The rate of fires per 10,000 buildings is under 30 for buildings containing and maisonette or flat, a social housing dwelling and a HMO.

5.2.9 The rate of deaths and casualties per 10,000 buildings is also much higher for residential care buildings and sheltered housing.

Table 5.3: Average Annual Prevalence of Fires, Deaths and Casualties by Building Type, 2017/18 to 2021/22

	Building Stock	Per 10,000 Properties of Each Type:
		Fires	Deaths	Casualties
Enclosed shopping centres	22,4001	81.0	0.1	2.5
Residential care building	1,1002	1,158.1	1.9	46.8
Sheltered housing complex	20,5003	211.8	1.3	23.3
Building with flat/maisonette	864,2004	29.2	0.2	6.0
Social housing dwelling	2,645,3005	33.87	0.27	6.27
Share multi-occ. residential building	9,9006	26.2	0.0	2.6

Notes: All data are rounded

1: Scottish Annual Business Statistics, Scottish Government, Data for 2020

2: Care Home Census for Adults in Scotland, Public Health Scotland, Data for 2021

3: Housing Statistics, Scottish Government, Data for 2021 includes very sheltered, sheltered and medium dependency housing for older people

4: 2011 Census - flat, maisonette or apartment. Data for 2011

5: Housing Statistics, Scottish Government, Data for 2020. Total dwellings (houses and flats)

6: Housing Statistics, Scottish Government, Data for 2021. Licenses for landlords and lodgers, bedsits and flats/houses to let.

7: Number of fires, deaths and casualties has been doubled to reflect the effect of deprivation.

5.3 The Value of a Statistical Life

5.3.1 The previous studies consistently used UK Government data on the value of a life. The latest available data (uprated to 2023 prices) are:

• The average value of preventing a fatal casualty is £2.3 million.
• The average value of preventing a serious casualty is £0.257 million.
• The average value of preventing a slight casualty is £0.020 million.

5.3.2 The data on casualties analysed in Figures 2.3 and 2.4 do not distinguish between serious and slight casualties. The severity of injury in Figure 2.5 shows that, on average over the last five years:

i. 25.8% of non-fatal casualties in dwelling fires were recommended to have a precautionary check.

ii. 39.7% of non-fatal casualties in dwelling fires received first aid at the scene.

iii. 29.9% of non-fatal casualties in dwelling fires were taken to hospital with slight injuries.

iv. 4.6% of non-fatal casualties in dwelling fires were taken to hospital with serious injuries.

5.3.3 Assuming casualties in categories (i) to (iii) above are classified as slight casualties and those taken to hospital with serious injuries (iv above) are classified as serious casualties, the weighted average value of preventing a casualty is £30,600. This value will be used in the cost benefit analysis.

5.4 The Value of Property Damage

5.4.1 The previous studies adopted a value of property damage per fire from a 2003 UK Government publication which was reported in the BRE 2004 report. The average property loss per fire was £7,100 for domestic properties and £22,600 for commercial properties (in 1999) prices. These figures were uprated to the relevant price base in the earlier studies.

5.4.2 The DCLG study found that average property damage was £2,600 per fire (2008 prices), but this included all fires including non-building and false alarms. Restricting property damage to building fires yields an estimate of £24,200 per building. This is substantially higher that the domestic estimates in the cost benefit studies.

5.4.3 The literature review did not identify any recent research on the cost of fire, although evidence from the Grenfell Tower fire estimates the cost to the council as over £400 million. This includes over £200 million of capital expenditure on new properties and £130 million on emergency housing, social care and well-being.

5.4.4 A fire in a high-rise block of flats in Glasgow in 2009 resulted in one fatality and two people needing hospital treatment. Of the 77 residents in the flats, only 18 were able to return to their homes in the immediate aftermath of the fire with some tenants out of their homes for many months. The cost of rehousing, refurbishment and loss of revenue was estimated at £2.6 million.

5.4.5 These projects illustrate the substantial costs associated with a major fire, but these large fires are relatively rare and as a result, their inclusion in the analysis would be inappropriate.

5.4.6 In the absence of any new research on the average value of property damage per fire, data from the literature review will be adopted and uprated for this study. The estimates (in 2023 prices) of property damage per building fire are:

• £12,300 for domestic properties (from cost benefit studies).
• £47,000 for commercial properties (from cost benefit studies).
• £35,700 for buildings (from Economic Cost of Fire study).

5.4.7 The result from the Economic Cost of Fire study does not distinguish between building type. Hence the estimates for domestic and commercial properties are assumed for this analysis as the building categories in Standard 2.15 cover both domestic and commercial properties.

5.5 The Effectiveness of Sprinklers

5.5.1 The assumptions about the effectiveness of sprinklers in reducing deaths, injuries and damage in the previous studies are shown in Table 5.4.

Table 5.4: Assumptions about Effectiveness of Sprinklers, %

	Deaths	Injuries	Damage
BRE 2004	70%	30%	50%
FSA Critique of BRE 2004	100%	85%	90%
BRE 2009	90%	61%	75%
BRE 2012 (Chief Fire Officers)	90%	51% - 73%	87% - 93%
	62% - Elderly
	30% - disabled
BRE 2012 (Welsh Assembly Government	90% - 100%	62% - 64%	88% - 93%
Optimal Economics 2015	95%	60%	85%

5.5.2 A report on the effectiveness of sprinklers by Optimal Economics^[14] on behalf of the National Fire Chiefs Council and the National Fire Sprinkler Network found that sprinklers are highly reliable and effective. They work as intended in 94% of cases and control or extinguish fires in 99% of cases. The study also found that fires in residential buildings where sprinklers operated had an average area of fire damage of under 4 sqm. This compared to an average area of fire damage of 18 to 21 sqm for all dwelling fires in England between 2011/12 and 2015/16.

5.5.3 Following this research, supplementary analysis^[15] was undertaken to assess the impact of sprinklers on fire fatalities and injuries. The analysis found that, on average, there is a fatal casualty every 142.5^[16] dwelling fires. Where sprinklers were present in fires, only five fatalities were reported.

5.5.4 Further study of these five fatalities found that the circumstances of the fire were outside the life-saving operating parameters of the system. Typically, the casualty was directly involved in the fire with either their clothing or bedding ignited. The casualties were often unable to move away from the fire or remove clothing due to mobility issues and were often vulnerable due to age or infirmity.

5.5.5 The analysis also found that where sprinklers are present, the rate of injury is around half that experienced in dwellings where sprinklers are not present. In general, there is a non-fatal casualty every 5.3 fires, but when sprinklers are fitted, this reduces to one in every 10 to 11 fires. The analysis also found that where a person is injured in a fire where a sprinkler system has activated, the severity of the injury is less and the need to receive hospital treatment is reduced.

5.5.6 From the review of literature, it is proposed to adopt the following assumptions for the effectiveness of the sprinkler system in preventing:

• Deaths – 95%.
• Injuries – 60%.
• Damage – 85%.

5.6 Estimates of Benefits

5.6.1 To derive an estimate of the benefit of preventing a death, the number of deaths per 10,000 buildings is multiplied by the value of a statistical life. This figure is divided by 10,000 to give the average benefit per building of preventing a death. This figure is multiplied by the effectiveness of sprinklers in preventing death to yield the estimated benefit of a prevented death as a result of the sprinkler system. This process is repeated for injuries and property damage with the values of the benefits of preventing death, injuries and damage shown in Table 5.5.

Table 5.5: Annual Value of Benefit (Avoided Cost), £

	Deaths	Injuries	Damage
Retail	19.48	4.91	323.36
Residential Care	408.79	85.87	1,210.78
Sheltered Housing	277.45	43.04	221.40
Flat/Maisonette	32.36	11.03	30.51
Social Housing1	50.22	11.47	35.21
HMO	0	5.56	28.09

Notes:

1: Prevalence of fires, deaths and injuries per 10,000 buildings reflects an uplift to allow for the effect of deprivation as a proxy for social housing

5.6.2 As there have been no deaths in HMO buildings over the last five years, there is no benefit associated with a reduction in fatalities for these buildings. The very low number of deaths per 10,000 buildings in retail, buildings containing a flat or maisonette and social housing results in a relatively low value of benefit for the prevention of a death. In contrast, the relatively high number of deaths per 10,000 buildings in residential care and in sheltered housing results in a higher value of benefit for the prevention of death. A similar pattern emerges for the value of the benefit associated with preventing injuries.

5.6.3 The benefits from reduced damage are based on retail buildings being classified as commercial and the other buildings classified as domestic. The relatively high prevalence of fire in residential care buildings yields the very large benefit figure in Table 5.4.